1. Field of the Invention
The present invention relates to an apparatus for cutting trees and grinding and mulching tree stumps, and more particularly an attachment mounted on a self-propelled vehicle which cuts trees and grinds and mulches the resulting tree stumps, and a method of cutting trees and grinding and mulching the resulting tree stumps.
2. General Background
Several devices have been patented which are aimed at grinding tree stumps.
Ram Industries, Inc. U.S. Pat. No. 4,041,996 issued on Aug. 16, 1977, and entitled "Stump Eradicator" teaches a tree stump cutter having a rotating cylinder or drum having spaced and staggered cutters around its periphery, the drum being supported by a boom and pivoting arm controlled by hydraulic motors which also provide the force which rotates the drum. The apparatus is mounted on the hydraulically operated arm of a tractor-type vehicle and has an arcuate guard which extends over the rear portion of the drum to act as a shield against cuttings.
J. Kehler U.S. Pat. No. 3,044,509 issued on Jul. 17, 1962, and entitled "Tree Stump Cutter Attachment" discloses a hydraulically operable belt-driven tree stump cutter connected to a tractor and having a cylindrical drum rotating horizontally and having cutting teeth around its periphery. In operation, the power from the tractor provides a means to swing the drum either vertically or horizontally into position to cut tree stumps to ground level.
U.S. Pat. No. 5,158,126 entitled "Improvements In Tree Stump Grinders And Method Of Grinding Tree Stumps"; and U.S. Pat. No. 5,355,918 entitled "Grinder Beam Drive For A Tree Stump Grinder", both issued to W. J. Lang, disclose, as best seen in the Lang '126 patent, a tree stump grinder having a rotating cylindrical drum having a plurality of rows of cutting teeth thereon and an arcuate shield attached to the end of the backhoe arm for preventing the drum from throwing cuttings and other debris against the operator and directing the cuttings toward the ground.
Vermeer Manufacturing Co. U.S. Pat. No. 4,848,423 issued on Jul. 18, 1989 and entitled "Guard Unit For A Stump Removing Machine Cutter Wheel" discloses a stump grinder having a rotating cylindrical cutting wheel having cutting teeth and a cutter wheel guard attached to a frame member which is movable about the top surface of the stump to be removed. A belt-driven assembly rotates the drum.
E. A. McKoy et al. U.S. Pat. No. 1,312,450 issued on Aug. 5, 1919 and entitled "Disintegrating And Conserving Mechanism" discloses a stump grinder that has a rotary cutting drum that is belt-driven and has a guard plate for deflecting cuttings thrown tangentially forward from the drum.
Other patents present in the art are Wood Technology, Inc. U.S. Pat. No. 5,070,920 issued on Dec. 10, 1991, and entitled "Debarker Knife Assembly"; Ram Industries, Inc. U.S. Pat. No. 4,180,107 issued on Dec. 25, 1979, and entitled "Stump Eradicator"; all of which are directed to a tree stump grinder, but do not meet the needs of the apparatus of the present invention. In particular, the above-mentioned prior art patents teach a tree stump cutter mounting an arcuate shield that only covers the forward or rearward surface of the cutting drum, not a semi-spherical arcuate shield that covers the entire upper surface of the cutting drum. Thus, the prior art arcuate shields provide inadequate protection to the operator of the apparatus. Furthermore, the above-mentioned prior art patents do not teach a tree stump grinder having a rotating cylindrical cutting drum with an arcuate shield that is positioned a constant radial distance from the drum to reduce the size of the wood shavings. Also, the above-mentioned prior art patents do not teach a method of cutting a tree and grinding and mulching the resulting tree plus the stump, only a method of grinding a tree stump.
Thus, a need exists for an apparatus which can quickly and efficiently cut, chip and mulch the trees and grind and mulch the resulting tree stump, the apparatus having a cylindrical cutting drum with a semi-spherical arcuate shield that covers the forward and rearward surface of the cutting drum and is positioned a constant radial distance from the cutting drum. Also, a need exists for a method of quickly and efficiently cutting, chipping and mulching trees and grinding and mulching the resulting tree stumps.